Joseph Gordon-Levitt struggled after filming ’50/50′

Joseph Gordon-Levitt was confronted by his own mortality fears as he portrayed a cancer victim in new movie “50/50″ and constantly worried about “what it would be like” if he was dying.

The “Inception” star, whose beloved older brother Dan died last October, admits filming the emotional film took its toll on him, and he often found himself wondering if he was suffering from the disease.

He tells BlackBook magazine, “We had a very upbeat, positive, collaborative set. It was never depressing to come to work…

“(But) that entire time, I never stopped thinking about what it would be like if I was about to die, and that’s rough. After we finished shooting the movie, I went through this phase where I had to say to myself, I don’t have cancer. I do not have cancer. It was like I needed convincing.”